This invention relates generally to tire-making equipment and relates, more particularly, to apparatus which defines an outer circumference, or circumferential surface, which serves as a forming surface or for grasping the inner surface of a tubular (e.g. tire-shaped) object or for defining an inner circumference for grasping the outer surface of a circular, tubular or round object.
The tire-making equipment with which this invention is concerned includes belt and tread drums whose outer circumferential surface is capable of expanding and contracting and a transfer ring whose inner circumferential surface is capable of expanding and contracting. In the case of a belt and tread drum, the capacity of the outer circumferential surface to expand and contract accommodates the removal of a completed package from the drum circumference and to enable a single drum to be used to form belt and tread packages of alternative diameters. In the case of a transfer ring, the capacity of the inner circumferential surface to expand and contract enables the transfer ring to grasp or release the outer circumference of a belt and tread package when the transfer ring is positioned thereabout.
Conventional designs of the circumferential surfaces of such tire-making equipment involve the use of a plurality of multi-section segments disposed about a common centerline and whose outer or inner surfaces collectively define the circumferential surfaces. preferably, such multi-section segments are capable of moving relative to one another during the equipment expansion or contraction process so that the uniformity (i.e. the rounded nature) of the circumferential surface is not appreciably sacrificed. Unless such a uniformity of the circumferential surface is preserved between the expanded and contracted conditions of the equipment, bumps or non-rounded regions which may otherwise be formed about the circumferential surface are likely to contribute to inaccuracies formed within a tire component built upon or engaged by the circumferential surface of the equipment. The multi-sectional segments of one such prior art design is shown and described in U.S. Pat. No. 5,635,016, the disclosure of which is incorporated herein by reference.
Heretofore, prior art schemes for moving the circumference-defining segments of a drum, such as the drum of the referenced patent, toward or away from the longitudinal centerline of the drum for the purpose of collapsing or expanding the drum have involved a cam element which is slidably accepted by radially-extending slots provided in the drum equipment and which is radially moveable with respect to the drum centerline. By moving the opposite ends of the drum toward or away from one another, mechanisms associated with the cam plate radially shift the circumference-defining segments toward or away from the longitudinal centerline of the drum to thereby alter the diameter of the drum circumference.
However, prior art schemes for altering the diameter of a drum such as that described in the referenced patent are limited in that they cannot move the circumference-defining segments through a relatively broad range of movement. In other words, prior schemes for altering the diameter of drums having an adjustable diameters have been incapable of altering the diameter of the drums through a relatively broad range. Such limitations could, for example, be due to the physical limitations of the equipment or the extent to which the multiple circumference-defining segments could be moved away from one another and still provide adequate support along the circumference of the drum for the tire component intended to be engaged at the surface. In any event, such factors limit the capabilities of prior art schemes to expand (or collapse) the circumference-defining segments of known drums to a maximum range of about 1.4 to 1.
It would be desirable to provide a new and improved scheme for altering the diameter of a drum or transfer ring having a circumference of adjustable diameter which is capable of moving circumference-defining segments through a relatively broad range of radial displacement.
Accordingly, it is an object of the present invention to provide a new and improved diameter-adjusting assembly for incorporation into a drum or transfer ring having a circumference of adjustable diameter and which is capable of altering the diameter of such a drum or transfer ring through a relatively broad range of diameters.
Another object of the present invention is to provide such an assembly which is capable of expanding (or collapsing) the circumference-defining segments of a drum or transfer ring through a range as high as about 1.85 to 1 and provide still stable support for a tire component expected to engage the circumference at either end of the range.
Still another object of the present invention is to provide such an assembly which is relatively uncomplicated in structure, yet effective in operation.